A plasma display has electric discharge caused in discharge spaces formed between a front glass substrate and a rear glass substrate. The discharge yield ultraviolet rays with 147 nm as the central wavelength to be generated from xenon gas, and the ultraviolet rays excite phosphor to allow display. If discharge cells respectively selectively coated with any of phosphor emitting light of red, green and blue are caused to emit light by a drive circuit, they can display in full color.
A recently actively developed AC type plasma display has a structure in which a front glass substrate with display electrodes, dielectric layer and protective layer and a rear glass substrate with address electrodes, dielectric layer, barrier ribs and phosphor layer are bonded together, and in which the discharge spaces partitioned by striped barrier ribs are filled with He—Xe or Ne—Xe mixed gas.
A conventional method mainly used for forming a phosphor layer of red, green and blue necessary for a plasma display is a screen printing method in which phosphor pastes are respectively consisting of a phosphor powder and a binder resin. In this method, a screen mesh provided with openings corresponding to the spaces between respectively adjacent barrier ribs and shielded by an emulsion on the other portions is coated with phosphor pastes, so that the phosphor pastes may be transferred through the screen mesh at the portions requiring the phosphor pastes, i.e., the spaces between the respectively adjacent barrier ribs.
Japanese Patent Laid-Open (Kokai) No. 6-5205 proposes a method of using sandblast after screen printing, and Japanese Patent Laid-Open (Kokai) No. 5-144375 proposes a method of screen printing after coating with a crosslinking agent.
However, the methods using screen printing have a disadvantage since the screen is changed in form by repeated printing, the accuracy is low, making it difficult to form a phosphor layer capable of providing a highly precise plasma display, and also have a problem that the cost is high since the expensive screen must be frequently exchanged.
One known method for forming a phosphor layer suitable for a highly precise plasma display is to use photosensitive phosphor pastes respectively consisting of a phosphor powder and a photosensitive binder resin. In this method, a substrate with barrier ribs is fully coated with the photosensitive pastes, consequently the coated film is partially exposed with UV light using a photo mask, to form portions soluble in a developer and portions insoluble in the developer, and are developed, to leave necessary portions. However, in this method, since layers of the respective phosphors of red (R), green (G) and blue (B) are formed, the complicated process of coating, exposure, development, drying, etc. must be repeated three times for R, G and B. The method also has a disadvantage that phosphor pastes are greatly lost, to raise the cost.
It is also proposed to eject a phosphor paste from the tip of an ink jet nozzle, for forming a phosphor layer. However, this method must keep the paste viscosity at 0.2 poise or less since the paste must be ejected from the tip of an ink jet nozzle with a small diameter. So, since the amount of the phosphor powder in the paste cannot be increased, the thickness of the phosphor layer cannot be controlled advantageously. Furthermore, this method also has such a problem that the ink jet nozzle is clogged by the phosphor powder and cannot be practically used.
It could therefore be helpful to provide a method for producing a plasma display capable of highly accurately and simply forming a phosphor layer in the spaces between highly precise barrier ribs and
An apparatus for producing the above high quality plasma display continuously at a high productivity level.